1.1.5 Fault-Tolerant & Resilient Applications

Fault-Tolerant & Resilient Applications

Retry Logic

• Exponential backoff with jitter
• AWS SDK tự động retry với exponential backoff
• Configurable: maxRetries, retryMode (standard, adaptive)

import boto3
from botocore.config import Config

config = Config(
    retries={'max_attempts': 5, 'mode': 'adaptive'}
)
client = boto3.client('dynamodb', config=config)

Circuit Breaker Pattern

• Ngăn cascade failures
• States: Closed → Open → Half-Open
• Khi error rate cao → circuit opens → fail fast

Idempotency

• Đảm bảo xử lý nhiều lần cho cùng kết quả
• Dùng idempotency token/key
• Quan trọng cho Lambda retries

Error Handling Best Practices

• Try/catch cho AWS SDK calls
• Handle specific exceptions (ThrottlingException, ServiceUnavailableException)
• Dead-letter queues cho failed messages
• Fallback responses cho graceful degradation